The proposed research project aims to characterize ultrastructural alterations which occur in renal cells after treatment with vinblastine sulfate, an oncolytic drug which interferes with the assembly of cytoplasmic microtubules. It is proposed that cytochemical procedures and transmission and scanning electron microscopy be used to study kidney tissue of rats given intravenous injections of vinblastine. The basic objectives are (1) to understand better the substructure of microtubules and vinblastine-induced structures comprised of microtubular protein, (2) to further our understanding of what functions microtubules perform in certain kidney cells, and (3) to characterize more fully some vinblastine-induced alterations which may shed light on the etiology of certain adverse side-effects of the chemotherapeutic use of this drug.